The U.S. Infant Mortality Rate: International Comparisons, Underlying Factors, and Federal Programs

Elayne J. Heisler
Analyst in Health Services

The infant mortality rate (IMR)—the number of deaths occurring in the first year of life per 1,000 live births—is a widely used proxy for the health status of a nation, and is commonly used for international comparisons. As of 2008, the U.S. IMR was 6.6, a historically low rate for the United States, but a rate that is still higher than the Organization for Economic Cooperation and Development (OECD) average of 4.6. The relatively high U.S. rate—and the number of infant deaths it indicates—concerns some policymakers. In addition, there is concern that the U.S. IMR has leveled off after four decades of decline. Reducing the U.S. IMR has been—and continues to be—a recognized public health objective.

Researchers and policymakers debate the various factors that may explain the high U.S. IMR relative to other developed countries and its recent stagnation. Potential factors include international differences in the recording of live births, different rates of low birthweight and short gestational age births, and racial and ethnic disparities. Researchers conclude that international recording differences do not explain the relatively high U.S. IMR. In addition, the data suggest that racial disparities may only partially explain the relatively high U.S. IMR. Instead, researchers suggest that higher U.S. rates of low birthweight and short gestational age births may explain the relatively high U.S. IMR.

This report examines the U.S. IMR. It identifies the top three causes of U.S. infant death— congenital malformations, disorders related to low birthweight and short gestational age, and sudden infant death syndrome (SIDS). The report focuses on low birthweight and short gestational age, because the United States has relatively high and increasing rates of these births, and research has found that these births can be reduced through policy interventions.

The U.S. IMR varies geographically and is influenced by a number of factors, including the mother’s demographic characteristics (e.g., education, income, or age) and health and health system characteristics. In general, southern states have the highest IMRs and states in New England and the Pacific Northwest have the lowest. The higher IMRs in southern states may be partially explained by higher rates of low birthweight and short gestational age births in these states. In addition, the racial and ethnic composition of a state’s population affects its IMR because of higher IMRs among certain racial and ethnic groups. The IMR is also influenced by health and health system characteristics, including the mother’s health behaviors, such as drinking and smoking, and her access to and use of prenatal care.

A number of federal programs that aim to improve the health status, and the economic and social circumstances, of low-income women and children may reduce the U.S. IMR. These programs include Healthy Start, Maternal and Child Health Services Block Grants, Medicaid, and the State Children’s Health Insurance Program (CHIP). Evaluating whether a particular program reduces the IMR is challenging because individuals may be eligible for multiple programs and because programs target those with IMR risk. Given this, it is difficult to determine the effectiveness of a single program, and it is difficult to determine whether findings that a program does not reduce the IMR are due to characteristics of the program or to characteristics of its participants.

The Patient Protection and Affordable Care Act (ACA, P.L. 111-148) either establishes new or expands existing programs to reduce the IMR. For example, “Strong Start,” funded by the new Center for Medicare & Medicaid Innovation created in the ACA, focuses on reducing the rate of pre-term births, which may also reduce the IMR once implemented.


Date of Report: April 4, 2012
Number of Pages: 34
Order Number: R41378
Price: $29.95

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